Sputtering machines are widely used in the coating process of display panels, such as OLED cathode coating or TP vanishing layer. Many coating processes do not require to form the film on the entire substrate but merely to deposit the film of the specific shape at the specific position. This requires the substrate to be tightly aligned with the metal mask when the substrate is coated and the relative position of the substrate and the metal mask to needs to be maintained after the alignment is completed, which cannot be changed at all during the entire film formation process. Therefore, the substrate clamping device is particularly important in the entire sputtering machine.
The current sputter substrate jig is generally mounted on the long side of the substrate. After the alignment is completed, the substrate is declined to the film deposition position. The substrate is clamped by using two or four jigs on the long side. Such jig design has the following defects: only fixtures on the two long sides do not guarantee that the short sides do not move during the film formation process; the clamping and loosening of such fixtures require the motor driving at both sides, however, the number of fixtures cannot be more with the restriction of the limited space of the coating chamber; the metal mask mounted on the fixtures has to be disassembled and verified every time for replacing the metal mask model, which will waste time and affect production capacity; frequently disassembled components are easily damaged to increase costs; it is easy to cause warpage of the substrate and/or the metal mask caused by the uneven stress of the substrate to cause the shadow of the coating, which affects the film formation quality.
There are also some sputter machines that choose not to install fixtures but only utilize the gravity of the substrate itself and improve the vibration of the actuator to maintain the relative position of the substrate and the metal mask. However, in case that the fixture is not used, once the transmission mechanism of the device vibrates, it will cause a change in the relative position.